Production of alizarin.



'tlINlTElU STATES PATENT OFFlCE.

CARL MOLLENHOFF, 0F LEVERKUSEN, NEAR COLOGNE, GERMAN-Y, ASSIGN OR TOFAR- BENFABRIKEN VORIVL FRIEDR. BAYER & 00., OF ELLBERFELD, GERMANY, ACOR- PORATION 0F GERMANY.

PRODUCTION OF ALIZARIN.

No lirawing.

To all whom it may concern:

Be it known that I, CARL MoLLENnoFF, doctor of philosophy, chemist,citizen of the German Empire, residing at-Leverkusen, near Cologne,Germany, have invented new and useful Improvements in the Production ofAlizarin, of which the following is a specification.

The direct conversion of anthraquinone into alizarin was alwaysattempted by the action of concentrated alkalis- (either them selves orin the presence of oxidizing agents or of reducing agents) onanthraquinone. I

l have now discovered that alizarin can be produced in a technicallysuccessful manner from anthraquinone by the action of a dilute alkali,(i. c. alkali lye containing less than 50 per cent. of alkali), if thereaction is carried out in the presence of an anthraquinone sulfonicacid and either with or without the addition of oxidizing agents.

In order to illustrate the new process more fully the-following exampleis given, the parts being by weight :-100 parts ofanthraquinone-beta-sulfonic acid, (sodium salt,) 50 parts ofanth'raquinone, -5 parts of saltpeter, (NaNO,,) 1425 parts of a 28 percent; caustic soda lye are filled in an autoclave and are then heated inan oil bath for 3 to 4 days to form ISO-200 C. The prodnot ofthereaction is dissolved in water, air is passed through the solution tooxidize any products of reduction which may be 7 present, the liquid isfilteredfand from the Specification of Letters Patent.

Application filed October 3, 1911. Serial No. 652,642.

Patented Aug. 27, 1912.

2. Process for the production of alizarin,

which process consists in heating anthraquinone with a dilute alkali ofless than 50 per cent. strength, an anthraquinone sulfonic acid and anoxidizing agent, substantially as described.

3. Process for the production of alizarin, which process comprisesheating anthraquinone with a dilute caustic soda lye of less than 50 percent. strength and an anthraquinone sulfonic acid, substantially asdescribed.

4. Process for the production of alizarin, which process consists inheating anthraquinone with a dilute caustic soda lye of less than 50 percent. strength, an anthraquinonc sulfonic acid and saltpeteiysubstantially as described.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing witnesses.

CARL MoLL'ENHoFr. [1,. 3.

Witnesses L. NUFER; ALBERT NUFER.

g the Commissioner of Patents,

Washington, D. C.

